hg-core: remove useless code (D8958#inline-14988 followup)

Differential Revision: https://phab.mercurial-scm.org/D9099

rust/hg-core/src/revlog/patch.rs

@@ -253,7 +253,7 b' mod tests {'
         }
 
         pub fn get(&mut self) -> &[u8] {
-            &self.data[..]
+            &self.data
         }
     }